ASW / ASM — non-linear medium-voltage surge arresters 6–30 kV
ASM and ASW are gapless metal-oxide surge arresters for medium-voltage AC networks of 6, 10, 15, 20 and 30 kV with a continuous operating voltage Uc from 4 to 36 kV. They protect the insulation of electrical equipment against lightning and switching overvoltages. ASM are intended for outdoor installation on overhead lines, ASW for indoor installation in switchgear.
- Type
- gapless metal-oxide (ZnO) arresters
- ASM
- outdoor, housing of liquid silicone LSR
- ASW
- indoor
- Continuous operating voltage Uc
- 4–36 kV
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
The main part of the arrester is a column of zinc oxide varistors with additions of oxides of other metals. The varistors are made by a specialized ceramic technology, so the voltage-current characteristic is strongly non-linear, the current handling capability is high, and the electrical parameters remain stable over many years of operation under operating voltage. During an overvoltage the conductivity of the varistors increases, the charge is discharged to ground, and with a correct choice of arrester the residual voltage at the terminals does not exceed a value safe for the insulation. After the return to operating voltage the arrester gives off heat to the environment and goes into standby mode, without interfering with network operation.
The varistor column is placed in the insulating material of the inner housing with high mechanical strength, aluminium electrodes are fitted on both sides, and the contact is held by pressure. In the ASM the outer housing is cast from liquid silicone LSR by direct moulding, there are no air inclusions, and this is confirmed by partial discharge measurements during acceptance tests. Silicone is hydrophobic, passes this property to the contamination layer and is self-cleaning. The housing is solid, without fitted sheds, so dirt does not accumulate at the joint. If the varistors are damaged, the short-circuit current does not cause a dangerous rupture of the housing, as happens in arresters with a porcelain housing.
The arresters comply with PN-EN 60099-4 and are made for networks with Un of 6, 10, 15, 20 and 30 kV (Um 7.2–36 kV). The short-circuit current withstand is 31.5 kA, the distribution class is DH, and the partial discharge level at 1.05 Uc is well below 10 pC. The mechanical strength of the ASM is SLL 150 Nm and SSL 250 Nm. ASM operate at temperatures from −55 to +55 °C at altitudes up to 1,000 m, in any position from vertical to horizontal. They can also be used as auxiliary support insulators, for example at pole-mounted transformer substations. Uc is selected taking into account the neutral earthing mode and the duration of a single-phase earth fault.
ASM are installed to protect MV cables at down-leads from overhead lines and at simplified 15/0.4 kV substations. ASW are mounted in switchgear cells, in particular ASW-18N arresters are used in PEGASO switchgear of the same manufacturer.
Technical specifications
| Type | gapless metal-oxide (ZnO) arresters |
|---|---|
| ASM | outdoor, housing of liquid silicone LSR |
| ASW | indoor |
| Continuous operating voltage Uc | 4–36 kV |
| Networks | Un 6–30 kV (Um 7.2–36 kV) |
| Short-circuit current (withstand) | 31.5 kA |
| Class | DH (distribution) |
| ASM mechanics | SLL 150 Nm, SSL 250 Nm |
| Temperature | −55…+55 °C (ASM) |
| Standard | PN-EN 60099-4 |
Request a price and lead time
ASW / ASM — non-linear medium-voltage surge arresters 6–30 kV. We reply within one business day.
Or email sales@usk.ua or call 044 339-50-20.
Questions and answers
For which network voltages are ASM and ASW arresters made?
For AC networks with Un of 6, 10, 15, 20 and 30 kV and a continuous operating voltage Uc from 4 to 36 kV. Uc is selected taking into account the neutral earthing mode and the duration of a single-phase earth fault.
How do ASM and ASW differ?
ASM are intended for outdoor installation on overhead lines and have a housing of liquid silicone LSR. ASW are installed inside switchgear and switchgear cells.
What short-circuit current withstand and class do the arresters have?
The short-circuit current withstand is 31.5 kA, the distribution class is DH according to PN-EN 60099-4. The mechanical strength of the ASM is SLL 150 Nm and SSL 250 Nm.
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